Centrifugal pump

ABSTRACT

This invention relates to a centrifugal pump which starts automatically and imparts a pulsating flow to liquid in the pump. The pump is provided with a volute chamber having an impeller driven by a motor centrally located therein and an air-liquid separating chamber having a right-triangular cross-section. The volute chamber and the separating chamber are connected. In the air-liquid separating chamber, liquid exhausted from the volute chamber first hits against an inclined plane, and then passes by a bottom plane, having a certain angle theta with respect to said inclined plane. The liquid then hits the lower part of the inclined plane to temporarily stop the flow of the liquid exhausted from the volute chamber.

United States Patent [191 Aga [ CENTRIFUGAL PUMP (76] Inventor: Yutaka Aga. 603 Higashiune, Akoh,

Japan [22] Filed: Nov. 27, 1973 [21] Appl. No: 419,388

[451 July 8,1975

Primary Examiner-C. .1. Husar Assistant Examiner-L. .l. Casaregola Attorney, Agent, or Firm-Fidelman, Wolffe & Leitner 5 7 ABSTRACT This invention relates to a centrifugal pump which starts automatically and imparts a pulsating flow to liquid in the pump. The pump is provided with a volute chamber having an impeller driven by a motor centrally located therein and an air-liquid separating chamber having a right-triangular cross-section. The volute chamber and the separating chamber are connected. In the air-liquid separating chamber, liquid exhausted from the volute chamber first hits against an inclined plane, and then passes by a bottom plane, having a certain angle 6 with respect to said inclined plane, The liquid then hits the lower part of the in clined plane to temporarily stop the flow of the liquid exhausted from the volute chamber.

4 Claims, 9 Drawing Figures PATENTED JUL 8 75 SHEET F G. PriorArt FIG.2(B)

CENTRIFUGAL PUMP SUMMARY OF THE INVENTION This invention relates mainly to a pump suitable for pumping a liquid and especially to improvements in self-priming centrifugal pumps.

FIG. 1 shows one example of a self-priming centrifugal pump which is already known. An impeller 13 having blades 12 fixed outside a rotor 11 is supported in a volute chamber 14. An L-shaped exhaust pipe 15 is connected with an exhaust port of said volute chamber 14. A wall 16 is provided between said volute chamber 14 and the exhaust pipe 15 and there is a hole 17 for reinduction at said wall 16.

In the pump of the above structure, the hole 17 is necessary to make some mixture of air and liquid in the volute chamber 14 which is necessary for exhausting air from the volute chamber 14 when the pump starts. However, if this small hole 17 happens to become clogged with some mixture in the liquid while the pump is operating, the hole does not function effectively. Moreover, as is clear from the movement of the liquid in the pump, shown by arrows in FIG. 1, after the pumping operation is started, the liquid inducted through the hole 17 collides with the liquid flow caused by the impeller 13 in the volute chamber 14, so that the pumping efficiency is lowered.

The main object of this invention is to overcome such a defect. The first feature of this invention is to provide, instead of said exhaust pipe 15, an air-liquid separating chamber having a right triangular cross-section and further having an inclined plane which when hit by the liquid causes the liquid to revolve, thereby separating air from the liquid exhausting air and insuring reliable operation of the pump.

The second feature of this invention is to eliminate the reinduction hole to improve the efficiency of the pump during the pumping operation.

The other features of this invention will be explained in the detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 is a vertical sectional view of the main part of a prior art pump;

FIGS. 2 (A), (B) and (C) are all vertical sectional views of the main part of one example of this invention showing the basic structure and the operating condition of the pump;

FIG. 3 is a cross-sectional view taken along III [II of FIG. 2 (B);

FIG. 4 is a front elevational view showing one example of the embodiment of this invention;

FIG. 5 is a right-side elevational view showing the embodiment of FIG. 4;

FIG. 6 is a diagram comparing the efficiency of the pump of this invention with that of a conventional pump under the same condition; and

FIG. 7 is a diagram comparing efficiency of the pumps of different types and sizes.

DETAILED DESCRIPTION OF THE INVENTION:

FIGS. 2 (A), (B) and (C) and FIG. 3 are vertical sectional views showing the basic structure and operative principles of the pump of this invention. The pump includes a casing 21 which is provided with a volute chamber 22 at the lower part thereof and an air-liquid separating chamber 23 at the upper part thereof. The

chambers 22 and 23 are connected with each other. Said volute chamber 22 has a rotating shaft 24 driven with a motor and said shaft 24 has an impeller 27 consisting of a rotor 25 having blades 26 fitted into its forward end. Said air-liquid separating chamber 23 has a right'triangular cross-section having a gradient 0 of about 30-45. The bottom corner of the chamber 23 is open to an exhaust port of the volute chamber 22. X is an oblique planar surface equivalent to an oblique side of said triangular cross section. 28 is a wall separating the volute chamber 22 from the air-liquid separating chamber 23, and the top surface of the wall 28 is the bottom planar surface y of the air-liquid separating chamber 23. The tips of the blades 26 of the impeller 27 touch the bottom surface of the wall 28. The angle of a corner W between the forward end surface 2 of the wall 28 and the bottom surface Y of the air-liquid separating room 23 is approximately 29 is an induction port of the pump, 30 an exhaust port, and 3! a housing for securing the rotating shaft 24 and the rotor 25.

Basic structure of the pump of this invention has been explained. In the embodiment as shown in FIGS. 4 and 5, a bearing support 32 is provided at the rearward portion of the shaft 24 to firmly secure it. The end of the shaft 24 is connected to a driving unit of a motor (not shown). 33 is a bracket for securing the bearing support 32 with the pump casing 21, and 34 is a base on which a driving unit of a motor and the pump is installed.

The operation of the pump in the above structure will be described hereinbelow according to FIGS. 2 (A), (B) and (C).

1. FIG. 2 (A) shows the pump when it is not in operation and FIG. 2 (B) shows the same in operation (when the impeller 27 is rotating). When the pump starts, air inside an induction pipe (not shown) connected to the induction port 29 and the volute chamber 22 begins to be mixed with remaining liquid and exhausted to the air-liquid separating chamber 23.

2. As soon as the above mentioned mixture is exhausted, liquid is inducted gradually from the induction port 29 with some remaining air. The mixture of air and liquid in the air-liquid separating chamber 23 flows as shown by arrows in FIG. 2 (B) and collides with the inclined plane X.

3. At the next stage as shown in FIG. 2 (C), the flow of the mixture in the chamber 23 becomes fast and a core m of eddy currents forms at the upper part of the chamber 23, and thereby air is separated from liquid again and exhausted from the exhaust port 30.

4. Simultaneously with the above operation, at the lower part of the chamber 23 liquid collides with the bottom surface Y and then further collides with the bottom corner of the chamber 23 causing the flow n which prevents the exhaust from chamber 22 from entering chamber 23. This flow n causes the liquid to move downward along the forward end surface Z of the wall 28 and then flow to the impeller 27 (shown by 0) to be cycled again in the volute chamber 22. Subsequently the same operation as mentioned above is repeated to exhaust air.

The liquid flow n intermittently stops the exhausting from the chamber 22 while the pump is in self-priming operation anad generates pulsating effect so that it works as a piston to exhaust air inside the pump by means of the cyclic liquid. The inventor has named this flow as shutter flow. Therefore the above pulsating flow is made by momentary repetition of air-liquid exhaustion and shutter flow, and continues during this selfpriming operation.

In the air-liquid separating chamber 23, the bottom surface Y, the bottom corner W and the plane X inclined with respect to the surface Y angle 6, have a special relationship for effectively separating air from liquid by utilizing the eddy flow generated in the chamber 23 and for exhausting air by generating ideal shutter flow.

FIG. 6 is a diagram comparing the efficiency of the pump of this invention with that of the conventional pump under the same condition.

Reference characters in HQ 6 mean as follows;

Q efficiency of the pump of this invention q efficiency of the conventional pump H total head P power V volume of lifting liquid Conditions in the measurement shown in FIG. 6 are;

Revolution (constant): 1800 r.p.m.

Nos. of blades of impeller: 3

Inner diameter of induction port: 2 inches FIG. 7 is a diagram comparing efficiency of pumps of different type and size.

Reference characters in FIG. 7 mean as follows;

0, efficiency of the pump of this invention in which the inner diameter of induction port and exhaust port is 2 inches.

Q efficiency of the pump of this invention in which the inner diameter of induction port and exhaust port is 2 /2 inches.

; efficiency of the pump of this invention in which the inner diameter of induction port and exhaust port is 3 inches.

q efficiency of conventional pump in which a hole for reinduction is provided and the inner diameter of induction port and exhaust port is 2 inches.

V volume of lifting liquid Conditions in the measurement shown in FIG. 7 are;

Revolution (constant): 1760 r.p.m.

Nos. of blades of impeller: 6

As it is clear from the drawings, efficiency of the conventional pump having a hole for reinduction is lower than 50 percent and that of the pump of this invention reaches nearly 60 percent. Moreover the pump of this invention is not provided with a hole for reinduction, and therefore does not have the problem of the hole becoming clogged by the mixture in the liquid, which the conventional pump has.

I claim:

1. A centrifugal pump comprising:

a volute chamber having a rotary impeller supported therein, and an air-liquid separating chamber having a substantially right-triangular cross-section and including a bottom planar surface and an oblique planar surface which is inclined with respect to said bottom surface, said bottom surface having an opening therein adjacent one end of said oblique surface, said opening connecting said volute chamber with said separating chamber, and said separating chamber further including an exhaust port adjacent a second end of said oblique surface.

2. A centrifugal pump, as set forth in claim 1, wherein said oblique surface is inclined with respect to said bottom surface at an angle between 30 and 45.

3. A centrifugal pump, as set forth in claim 1, further including a wall separating said volute chamber from said separating chamber, a first surface of said wall forming a portion of said bottom surface and a second surface of said wall forming a top portion of said volute chamber.

4. A centrifugal pump, as set forth in claim 3, wherein said wall further includes an end surface which is substantially perpendicular to said first surface, said end surface forming part of an exhaust port from said volute chamber. 

1. A centrifugal pump comprising: a volute chamber having a rotary impeller supported therein, and an air-liquid separating chamber having a substantially righttriangular cross-section and including a bottom planar surface and an oblique planar surface which is inclined with respect to said bottom surface, said bottom surface having an opening therein adjacent one end of said oblique surface, said opening connecting said volute chamber with said separating chamber, and said separating chamber further including an exhaust port adjacent a second end of said oblique surface.
 2. A centrifugal pump, as set forth in claim 1, wherein said oblique surface is inclined with respect to said bottom surface at an angle between 30* and 45*.
 3. A centrifugal pump, as set forth in claim 1, further including a wall separating said volute chamber from said separating chamber, a first surface of said wall forming a portion of said bottom surface and a second surface of said wall forming a top portion of said volute chamber.
 4. A centrifugal pump, as set forth in claim 3, wherein said wall further includes an end surface which is substantially perpendicular to said first surface, said end surface forming part of an exhaust port from said volute chamber. 